Transarterial Infusiono fRadioactiveY_2O_3 Microspheresin Transplanted Liver Tumors in Rabbits

2004 Fiscal Year Final Research Report Summary

• Project/Area Number: 14570856
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Radiation science
• Research Institution: Kyoto University
• Principal Investigator: MITSUMORI Michihide Kyoto University, Graduate School Of Medicine and Faculty of Medicine, Associate Professor, 医学研究科, 講師 (10263089)
• Co-Investigator(Kenkyū-buntansha): NAGATA Yasushi Kyoto University, Graduate School Of Medicine and Faculty of Medicine, Professor, 医学研究科, 助教授 (10228033) ; ARAKI Morio Kyoto University, Graduate School Of Medicine and Faculty of Medicine, Assistant Professor, 医学研究科, 助手 (20362486)
• Project Period (FY): 2002 – 2004
• Keywords: Transarterial infusion / Yttrium Oxide / liver tumor / internal radiation therapy / VX2 tumor

Research Abstract

A novel intraarterial embolic material, a new type of radioactive Y_2O_3 microsphere forlivertumorshasbee developed. In this study, the therapeutic effet and the distribution of the material was evaluatedintherabbittumor model. Four to 5 pieces of VX2 tumor were transplanted into the liver of Japanese albino rabbit. Sixteen rabbits with 2 to 5 tumors were divided in to three groups, a non-treatment group (5 rabbits with 13 tumors : group A), a non-radioactive Y_2O_3 microsphere infusiongroup (5 rabbits with 25 tumors : group B) and a radioactive Y_2O_3 microsphere infusiongroup (6rabbits with 23 tumors : group C). Two weeks after tumor transplantation, 30 mg of the radioactive microsphere with 131-173 MBq or non-radioactive microsphere was infused in to the livers of the rabbits through the hepatic artery. Three weeks after infusion, the sizes of the VX2 tumors grown in the rabbits were measured by treatment groups. The concentrations of yttrium in the liver and in the tumor specimens were measured by tissue dissolution method. The migration of the material into the other organs was also investigated. The number of evaluate tumorswas13ingroupA, 25 in group B, and 23 in group C. The mean maximal diameter +SD of the group A 29.3 mm+5.44, 25.3mm +6.65 in group B, and 11.0 mm +6.71 in group C. Significant delay in growth were observedintumorstreated by the radioactive microsphere infusiongroupcomparedwiththenon-radioactivemicrosphere infusion group (t-test, P<0.005). No difference was observed between group A and group B. As very small amount of yttrium was detected in the stomach and in the duodenum, and no migration was detected in the distant organs.
The newly-developed radioactive Y_2O_3 microspheres seem useful as a infusion material for implanted liver tumors in the rabbit.